I think here there are only two ways:
1- If the memenu allows you to go offline, it should allow you to go back online.
2- If the memenu is not useful to come back online, then all IM-related items simply should be hidden. Maybe the memenu itself should.
If this applies to any other desktop item, I don't see why it shouldn't to memenu.
IMHO when a software behaves like that, it can be considered a kind of bug.
You can change the status to invalid, but the problem is still here.
I think here there are only two ways:
1- If the memenu allows you to go offline, it should allow you to go back online.
2- If the memenu is not useful to come back online, then all IM-related items simply should be hidden. Maybe the memenu itself should.
If this applies to any other desktop item, I don't see why it shouldn't to memenu.
IMHO when a software behaves like that, it can be considered a kind of bug.
You can change the status to invalid, but the problem is still here.